Q: Which AQL sampling plan fits zipper bulk inspection?
For most zipper shipments, general inspection level II with normal severity is a workable starting point, sampling by lot and by colour. If the lot is mixed, treat each colour and size as a separate lot for defect counting, because a shade problem in one colour should not be diluted by the rest. For large lots or high-risk customers, level III or a tightened scheme gives more evidence at a higher inspection cost.
Define the lot clearly: one purchase order, one size, one colour, one production run. Draw the sample randomly from across the cartons, not from the top layer. Inspect for the defect classes you defined, count them by class, and compare with the acceptance numbers. Where a defect is found late in the sample, complete the sample before deciding, since the plan assumes a full sample.
Record lot size, sample size, class counts, acceptance and rejection numbers, and the decision. If the lot is rejected, the supplier should sort or rework and resubmit, and the resubmitted lot should be inspected under tightened severity.